Editing Electromagnetic compatibility (section)

== Testing ==

Testing is required to confirm that a particular device meets the required standards. It is divided broadly into emissions testing and susceptibility testing. Open-area test sites, or OATS,<ref>{{Cite web | title=EMI/EMC Testing | url=https://discrete.co.in/blog/what-is-emiemc-testing-standards-list-procedure-types |access-date=2024-07-24 |website=discrete.co.in |language=en}}</ref> are the reference sites in most standards. They are especially useful for emissions testing of large equipment systems. However, RF testing of a physical prototype is most often carried out indoors, in a specialized EMC test chamber. Types of the chamber include [[Anechoic chamber#Radio-frequency anechoic chambers|anechoic]], [[Electromagnetic reverberation chamber|reverberation]] and the [[GTEM cell|gigahertz transverse electromagnetic cell]] (GTEM cell). Sometimes [[computational electromagnetics]] simulations are used to test virtual models. Like all compliance testing, it is important that the test equipment, including the test chamber or site and any software used, be properly calibrated and maintained. Typically, a given run of tests for a particular piece of equipment will require an ''EMC test plan'' and a follow-up ''test report''. The full test program may require the production of several such documents.

Emissions are typically measured for radiated field strength and where appropriate for conducted emissions along cables and wiring. Inductive (magnetic) and capacitive (electric) field strengths are near-field effects and are only important if the device under test (DUT) is designed for a location close to other electrical equipment. For conducted emissions, typical transducers include the [[Line Impedance Stabilization Network|LISN]] (line impedance stabilization network) or AMN (artificial mains network) and the RF [[current clamp]]. For radiated emission measurement, antennas are used as transducers. Typical antennas specified include [[Dipole antenna|dipole]], [[Biconical antenna|biconical]], [[Log-periodic antenna|log-periodic]], double ridged guide and conical log-spiral designs. Radiated emissions must be measured in all directions around the DUT. Specialized EMI test receivers or EMI analyzers are used for EMC compliance testing. These incorporate bandwidths and detectors as specified by international EMC standards. An EMI receiver may be based on a [[spectrum analyser]] to measure the emission levels of the DUT across a wide band of frequencies (frequency domain), or on a tunable narrower-band device which is swept through the desired frequency range. EMI receivers along with specified transducers can often be used for both conducted and radiated emissions. Pre-selector filters may also be used to reduce the effect of strong out-of-band signals on the front-end of the receiver. Some pulse emissions are more usefully characterized using an [[oscilloscope]] to capture the pulse waveform in the time domain.

Radiated field susceptibility testing typically involves a high-powered source of RF or EM energy and a radiating antenna to direct the energy at the potential victim or device under test (DUT). Conducted voltage and current susceptibility testing typically involves a high-powered signal generator, and a [[current clamp]] or other type of [[transformer]] to inject the test signal. Transient or EMP signals are used to test the immunity of the DUT against powerline disturbances including surges, lightning strikes and switching noise.<ref>[http://www.electronics-project-design.com/EMCTesting.html EMC Testing and Standards in Transient Immunity Testing, RF Immunity]. Electronics-project-design.com. Retrieved on 2011-07-19.</ref> In motor vehicles, similar tests are performed on battery and signal lines.<ref>[http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=45931 ISO 7637-2:2004/Amd 1:2008]. Iso.org (2011-03-01). Retrieved on 2011-07-19.</ref><ref>[http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=40581 ISO 7637-3:2007 – Road vehicles – Electrical disturbances from conduction and coupling – Part 3: Electrical transient transmission by capacitive and inductive coupling via lines other than supply lines]. Iso.org (2010-09-06). Retrieved on 2011-07-19.</ref> The transient pulse may be generated digitally and passed through a broadband pulse amplifier, or applied directly to the transducer from a specialized pulse generator. [[Electrostatic discharge]] testing is typically performed with a [[piezo ignition|piezo spark generator]] called an "[[ESD pistol]]". Higher energy pulses, such as lightning or nuclear EMP simulations, can require a large [[current clamp]] or a large antenna which completely surrounds the DUT. Some antennas are so large that they are located outdoors, and care must be taken not to cause an EMP hazard to the surrounding environment.